I have a few lab questions..could someone check them for me?
1. 1-Benzylnicotinamide chloride can be prepared by heating nicotinamide with benzyl chloride in DMSO. Give a mechanism for the reaction and explain why alkylation occurs at the pyridine nitrogen. Why is DMSO a good solvent for this reaction?
Ans. Is this just a simple Sn2 reaction?
alkylation occurs at the pyridine nitrogen because amides are weaker nucleophiles
DMSO is dipolar aprotic solvent so nucleophile stays anionized but can be stabilized by polarity
2. 1-Benzylnicotinamide is similar to a naturally occuring enzyme cofactor that is used reduction/oxidation reactions. What is the name and structure?
3. Ethyl benzoylformate is not reduced by 1-benzyldihydronicotinamide alone. In the presence of magnesium chloride, however, racemic ethyl mandelate is formed in quantitative yield. Explain with a mechanism how MgCl2 accelerates the reaction.
Ans. MgCl2 could help stabilize the negative charge on the O on the carbonyl group being reduced?
4. When ethyl benzoylformate is treated with (R)-N-(alpha-methylbenzyl)- dihydronicotinamide in the presence of an equimolar amount of magnesium chloride in aqueous acetonitrile solution, the ethyl mandelate produced is 60% R and 40% S.
a. Draw formulae indicating the structure and configuration of (R)-N-(alpha-methylbenzyl)- dihydronicotinamide and of the two enantiomers of ethyl mandelate.
are these correct?
How do we know which N the substituent is on? (for (R)-N-(alpha-methylbenzyl)- dihydronicotinamide)
b. Explain why the product is not a racemic mixture (you do not have to explain which enantiomer is favoured).
c. What is the enantiomeric excess of the ethyl mandelate?
Ans. I don't even understand this question
Could someone rephrase it for me?